Drilling attachment

ABSTRACT

In accordance with an illustrative embodiment of the present invention, a drilling attachment for use in conjunction with a crawler or a truck mounted crane includes a frame assembly pivoted at one end to the crane at the base of the boom and extending horizontally outwardly, a drilling unit on the frame assembly and including a drilling rotary mounted for pivotal rotation about a horizontal axis that is transverse with respect to said frame assembly, and a lead beam for supporting the frame assembly and drilling unit from the boom of the crane, said lead beam being attached at right angles to said drilling rotary and arranged to tilt in reaction to changes in boom angle and to pivot said drilling rotary to establish a desired drilling angle.

United States Patent [:9]

Wallace [54] DRILLING ATTACHMENT [75] Inventor: James L. Wallace, College Station,

Tex.

[73] Assignee: R. B. Butler, 1nc., Bryan, Tex. a

part interest [22] Filed: Apr. 28, 1971 [21] Appl. No.: 138,167

[52] U.S.Cl. [51] Int. Cl.

....173/43, 173/151, 173/165 ..E2lb 7/02 11/1970 lrons et a1 ..l73/44 X 11/1921 Bellony ..173/28 X Primary Examiner-Emest R. Purser Attorney-David L. Moseley [5 7] ABSTRACT In accordance with an illustrative embodiment of the present invention, a drilling attachment for use in conjunction with a crawler or a truck mounted crane includes a frame assembly pivoted at one end to the crane at the base of the boom and extending horizontally outwardly, a drilling unit on the frame assembly and including a drilling rotary mounted for pivotal rotation about a horizontal axis that is transverse with respect to said frame assembly, and a lead beam for supporting the frame assembly and drilling unit from the boom of the crane, said lead beam being attached at right angles to said drilling rotary and arranged to tilt in reaction to changes in boom angle and to pivot said drilling rotary to establish a desired drilling angle.

12 Claims, 7 Drawing Figures PATENTED W22 I975 sum 1 BF 2 T/LT AXIS James L Wallace INVENTOR BY mad ATTORNEY PATENTEU HAT 21m sum 2 BF 2 James L.Wallace INVENTOR ATTORNEY 1 DRILLING ATTACHMENT This invention relates generally to earth boring machines, and more particularly to a drilling apparatus that can be attached to a crawler or a truck mounted crane and is adapted for drilling either straight or inclined holes with great accuracy and minimum set-up time.

Construction requirements for numerous structures such as bridges, piers, foundations and the like call for hole drilling operations to enable supporting columns to be positioned in the earth. Particularly where the hole must be drilled at an angle to the vertical, special equipment is required. One example of this is in connection with the drilling of battered pilot holes for pile driving operations. In the past, various devices have been used to drill inclined holes, all of which have certain limitations. For example, some machines have a drill that operates at a fixed angle and thus suffer from a lack or versatility where different hole angles are required. Other machines have a drill shaft thatcan be tilted through a narrow range of angles, however, the engine that drives the drill shaft must also be tilted out of level, a factor-which amounts to a considerable disadvantage. Yet another limitation in prior devices is that they have been subject to a considerable amount of vibration during hole drilling operations, causing undue wear and tear on equipment. A particular problem in this area has been due to insufficient support for the drive kelly which has enabled it to undergo a whipping action during rotation.

Another significant problem has been encountered in the prior art in connection with the drilling of holes close to the edge of a header bank or other fill, which is a fairly common requirement in bridge construction. In the past, for example, drills have been mounted on cranes in close proximity to the crane chassis so that it was necessary to position the crane itself at the edge of the header bank. This creates a safety hazard to men and equipment, and it is desirable to provide a method of extending the drill with respect to the crane to enable such holesto be drilled while the crane remains on firm and level ground.

It is the principal object of this invention to provide a new and improved drilling apparatus that overcomes the disadvantages and problems noted above.

Another object of this invention is to provide a new and improved versatile drilling machine adapted to drill both straight and inclined holes and particularly for drilling inclined holes over a wide range of hold angles with great accuracy and minimum set-up time.

Another object of the present invention is to provide a new and improved drilling attachment for use in conjunction with a crawler or a truck mounted crane, the attachment being supported with respect to the crane in such a manner that vibration during drilling operations is held to a minimum.

A further object of the present invention is to provide a new and improved drilling attachment for a crane or the like, the attachment being constructed and arranged such that it can be used to drill holes near header banks or other fills in a safe manner.

These and other objects are attained in accordance with the concepts of the present invention through the provision of a drilling attachment comprising a frame assembly that is adapted to be connected in a horizontal or level position to the crane chassis at the base of the boom. The frame assembly carries a drilling rotary having a drive kelly extending therethrough, the rotary being mounted on trunnions to allow the rotary to tilt and remain square with the drive kelly at a desired drilling angle. A lead beam is fastened at right angles to the drilling rotary and extends upwardly in parallel alignment with the drive kelly. The upper end of the lead beam is attached to a cable that extends over one of the crown sheaves of the boom, with the result being that the drilling rotary is automatically tilted to obtain a new drilling angle anytime the boom angle is changed. Also, the lead beam is used to suspend the load of the frame assembly and rotary from the boom to minimize vibration and whipping action of the entire unit during a drilling operation.

In order to enable drilling high angle holes with minimum boom angle changes, as well as to enable extension over header banks or other fills while the crane remains on firm and level ground, the frame assembly is constituted by an elongated main; frame that is connected to the crane, and a separate frame that is positioned on top of the main frame with a slide assembly. The engine, transmission, drive components and drilling rotary are unitized on this separate frame, which enables the drilling unit to be positioned close to the crane or further away. Set screws or the like are provided to fix the frames in any one of a number of relative positions. Thus the drilling unit can be positioned along the main frame by loosening the set screws, engaging the drill with the ground, setting the boom in a desired position, and then walking the crane toward or away from the drilling unit as required. When the drilling unit is in the desired position with respect to the main frame, the set screws are locked to hold the drilling unit in fixed position on the main frame. For all relative positions on the frame, the drilling angle can be readily changed in response to changes in boom angle.

The present invention has other features and advantages which will become more fully apparent in connection with the following detailed description of a preferred embodiment thereof, taken together with the appended drawings in which:

FIG. 1 is a somewhat schematic view of the drilling attachment illustrated in conjunction with a crawler type crane;

FIG. 2 is an enlarged side view of the main and sliding frame structures and the drilling unit;

FIG. 3 is a cross-section taken on line 3-3 of FIG.

FIG. 4 is a top view to further illustrate the unitized engine, drive train and rotary components of the drilling unit;

FIGS. 5 and 6 are respective side and top sectional views of the kelly guide structure; and

FIG. 7 is a side elevation view of a telescoping kelly and guide roller assembly in accordance with one aspect of the present invention.

Referring initially to FIG. 1, a drilling attachment in accordance with the principles of this invention is indicated generally at 10 and is shown in connection with a crawler type crane 11. Of course it will be appreciated that the attachment 10 can be used with a truck mounted crane, and the present invention is not limited to use with any particular vehicle device. In typical fashion, the crane 10 has an upwardly extending boom 12 with crown sheaves l3 and 14 over which cables 15 and 16 are extended. The cables are controlled by a conventional draw works that is well known to those skilled in the art, and of course other cables (not shown) are used to change or control the boom angle. The drilling attachment includes a frame assembly 17 that is pivoted at its inner end to the chassis of the crane underneath the boom 12. The frame assembly 17 carries a drilling rotary 18 having a drive kelly 19 extending therethrough with a typical auger 20 mounted on the lower end of the kelly. As will be described in greater detail herebelow, the drilling rotary 18 is mounted on trunnions for pivotal rotation about a horizontal axis that is transverse to the frame assembly. A rigid lead beam 21 is attached at a right angle to the drilling rotary l8, and extends upwardly in parallel alignment with the drive kelly 19. The upper end of the lead beam 21 is attached by suitable means to the cable 15, with the result being that this cable and the lead beam actually suspend the frame assembly 17 and the drilling rotary 18 from the boom 12. A guide structure 22 is coupled to the upper end of the kelly 19 and is slidable longitudinally along the lead beam 21 during hole drilling operations.

Referring now to FIGS. 2 and 3, it will be seen that the frame assembly 17 is constituted by a main frame 23 that extends outwardly from the base of the boom 12, and a slidable frame 24 that is attached to the main frame. The main frame 23 has parallel side members 25 that are connected together by cross brace members (not shown). The inner ends of the side members 25 are connected to beams 26 having boom feet 27 pinned to the crane chassis. As can be seen from the drawing, the main frame 23 extends in a horizontal plane a substantial distance outwardly from the crane 11 underneath its boom 12. The slidable frame 24 is positioned on top of the main frame 23 and its connected thereto by a slide assembly so as to be movable longitudinally therealong. The frame 24 is constituted by a plurality of beams 29 extending across the main frame 23, the beams being connected together, for example, by plate members 31 to form a table construction. As shown in FIG. 3, L shaped members 33 are welded at each end of the respective beams 29, and the slide assembly is provided through the use of longitudinally extending runners 34 and 35 connected to the members 33 and 25, respectively. The runners 34 and 35 can be made from angle iron for convenience of construction and are welded or otherwise secured in place. Several set screws or bolts 36 extend upwardly through the runners 34 and are adapted to engage the runners 35 in order to fix the frames 23 and 24 against relative movement. Of course when the set screws are loosened, the slidable frame 24 can be moved longitudinally along the main frame 23 by a considerable amount. Two longitudinally disposed beams 37 overlap the front two of the cross beams 29 and are fixed thereto.

The drilling unit is mounted on the slidable frame 24, and includes the drilling rotary 18 that receives the drive kelly 19. The rotary assembly is not shown in detail but is constituted by the usual rotary table that is adapted to be turned by a ring gear and pinion. The table receives a kelly bushing 41 having guide rollers through which the kelly 19 extends. In accordance with one feature of this invention, the rotary 18 is mounted in a support frame 42 which is in turn pivotally mounted on the beams 37 by side trunnions 45 and bracket mounts 46 as shown in FIG. 4. Thus it will be apparent that the rotary assembly 18 can pivot about a horizontal axis that is transverse to the frame assembly 17 in order to establish various drilling angles with respect to vertical. The input shaft 47 for the gearing that causes the table of the rotary to turn is journaled in suitable support bearings (not shown) on the frame 42 and is located in such a manner that its rotation axis is aligned with the tilt axis of the rotary.

A suitable engine or motor 50 is mounted to the rear of the slidable frame 24 and supplies power through a suitable fluid drive clutch and a four-speed transmission to a belt drive 51. The belts drive an intermediate pulley 52 having a sprocket 53 that drives a roller chain 54. The chain 54 drives a sprocket wheel 55 on the input shaft 47 of the rotary 18. Ari-idler sprocket and chain slack adjustment can be provided but are not shown in order to simplify the description. In any event, the particular details of the motor, drive belts and chains form no part of the present invention. Particular note should be taken, however, of the fact that the engine 50 is mounted in a level position on the frame assembly and can remain level regardless of the angle of the drive kelly 19 and the rotary 18 as will become more fully apparent herebelow. Moreover, since the center line of the rotary drive shaft 47 is aligned with the tilt axis, the rotary 18 can be tilted without changing the length or pitch of the drive chain 54.

As shown in FIG. 2, and in accordance with a further feature of this invention, the lead beam 21, preferably in the form of an I beam, provides a stabilizing guide for the drive kelly 19. The lower end of the beam 21 is received within a bracket 59 that is rigidly secured to the rotary 18 by side posts 43 and braces 61. The bracket 59 includes spaced apart front and rear plates 48 and 49, and the lead beam is coupled to these plates by a king pin 60. Thus it will be appreciated that the lead beam 21 is attached at right angles to the drilling rotary 18, so that tilting of the lead beam in a fore and aft direction will cause corresponding tilt of the drilling rotary 18. On the other hand, the lead beam 21 is free to pivot about the pin 60 in a plane that is parallel to the tilt axis of the rotary 18 to accommodate misalignment where the crane gets out of level or the top of the boom is not properly centered with respect to the frame assembly 17, circumstances that might otherwise cause the lead beam to be bent. The beam 21 extends upwardly toward the boom 12 and has its upper end connected to the cable 15. Since the main frame 23 is pivotally connected to the crane 11 by a boom feet 27, the result is that the beam actually suspends the frame assembly 17 and the drilling unit from the boom 12. This manner of suspension has been found to hold to a minimum the vibration that may otherwise occur during a drilling operation. The lead beam 21 can be tilted by changing the angle of the boom 12, and since the beam is attached at right angles to the rotary 18 which is pivoted by the trunnions 45, the angle of the drive kelly 19 with respect to vertical can be changed or adjusted by changing or adjusting the boom angle.

within the housing 63. The housing 63 is attached by structural members 69 to a slide plate 70 that slides along the outer surface of the lead beam 21. Retainer plates 71 and 72 are attached by spacers and bolts to the slide plate 70 and are positioned on the inside surfaces of the beam 21. Thus it will be appreciated that the guide structure 22 will slide longitudinally along the beam 21 as the drive kelly 19 is lowered during a drilling operation and function to stabilize the kelly and prevent its upper end from undergoing any whipping action. The tubular sub 64 is coupled to the cable 16 by a conventional swivel (not shown) to enable the kelly to rotate freely as it is raised and lowered.

The drive kelly 19 can be a telescoping device with an inner member disposed within an outer member for drilling fairly deep holes. When a telescoping kelly is used, problems have been encountered in the prior art in' obtaining a smooth telescoping action due to the fact that torque from the rotary table was applied only to the outside kelly. Consequently, a considerable amount of friction was generated between wall surfaces of the members that tended to retard telescoping action. In accordance with a further feature of this invention, a guide roller assembly 75 is fixed to the bottom end of the outside kelly 76 as shown in FIG. 7. The assembly includes a mounting bracket 77 having set screws 78 and a housing 79 that receives rollers 80 and 81. The rollers engage the outer side surfaces of the inside kelly 82 and function to transmit torque thereto. It will be appreciated that this arrangement allows the inside kelly 82 to telescope freely while under load from turning, since the torque is supplied via the rollers rather than by the walls of the respective kellys. When telescoping kellys are used, the cable 16 is connected by a swivel 83 only to the inside kelly 82, and a lip or other suitable means (not shown) is provided at the upper end of the outside kelly 76 to limit its downward movement with respect to the inside kelly. Of course the guide structure 22 will stop downward movement when it reaches the top of the kelly bushing 41.

In operation, the structure is assembled as shown in the drawings with the main frame 23 pivoted to the crane chassis and the lead beam 21 attached to the cable 15. As previously noted, the lead beam 21 and the cable suspend the drilling unit and the frame assembly from the boom 12. The drilling unit is positioned at a selected point along the main frame 23 by letting the auger 20 down onto the ground, loosening the set screws 36 and then walking the crane 11 toward or away from the auger. When the desired drilling unit position is established, the set screws 36 are tightened to lock the frames 23 and 24 together. It will be appreciated that for inclined holes the hole angle can be established by the foregoing procedure, since the lead beam 21 will tilt as the lateral position of the drilling unit with respect to the crane is changed, assuming that there is no change in the boom angle. If needed the frames 23 and 24 can be leveled by taking in or letting out the cable 15. Drilling can then proceed.

As the auger 20 makes it way into the ground, the cable 16 is let out by the crane operator. The guide structure 22 causes the drive kelly 19 to remain in parallel alignment with the lead beam 21 during rotation and stabilizes the upper end of the kelly to eliminate any whipping action. The entire system operates relatively free of vibration due to the method of suspension from the boom 12. Moreover, the drive kelly 19 operates with minimum deflection since it remains square with the drilling rotary 18.

Most specified drilling angles can be obtained by simply changing the angle of the boom 12 without any other changes. As the boom angle is changed, the drilling rotary 18 will pivot on the trunnions 45 due to reactive tilting of the lead beam 21. The frame assemblies 23 and 24 can be leveled so that the engine 50 operates in a level position for any drilling angle.

The drilling unit can be extended over a header bank or other fill by locating the sliding frame 24 in its outermost position with respect to the main frame 23. Drilling operations can then be accomplished with the crane 11 resting on firm and level ground, a feature which yields a distinct safety advantage. Moreover, the drilling unit can be located in close proximity to the crane, which enables the unit to be: used with relatively small cranes for drilling vertical foundation and pier holes. Of course, even in the absence of header banks or other like conditions, it will be realized that holes can be drilled at extreme angles with minimum boom changes, due to the wide range of relative positions available for the frame assemblies 23 and 24.

Since certain changes or modifications may be made in the disclosed embodiment by those skilled in the art without departing from the inventive concepts involved, it is the aim of the following claims to cover all such changes or modifications falling within the true spirit and scope of the present invention.

I claim:

1. A drilling apparatus adapted for attachment to a crane having an upwardly extending boom, comprising: a generally horizontally disposed frame assembly having coupling means atone end for pivotally attaching said frame assembly to the crane at the base of the boom; a drilling unit mounted for movement relatively along at least a portion of said frame assembly between various fixed positions with respect thereto, said drilling unit including a drilling rotary mounted for pivotal movement about a horizontal axis that is transverse with respect to said frame assembly; and rigid lead means extending upwardly from said rotary for suspending said drilling unit and said frame assembly from the boom, said lead means being attached at right angles to said rotary and functioning to tilt said rotary in response to changes in boom angle to establish a desired drilling angle.

2. A drilling attachment for use in conjunction with a crane having an upwardly extending boom, comprising: a generally horizontally disposed frame assembly adapted to be pivotally connected to the crane at the base of the boom; a drilling unit mounted for movement relatively along at least a portion of said frame assembly between various fixed positions with respect thereto, said drilling unit including a drilling rotary attached for pivotal rotation about a horizontal axis that is transverse with respect to said frame assembly, and a drive kelly extending through said rotary; and lead means secured at right angles to said rotary and extending upwardly in parallel alignment with said drive kelly, said lead means being suspended from the boom in a manner to be tilted in response to changes in boom angle to automatically pivot said drilling unit and thereby establish a desired drilling angle.

3. The drilling attachment of claim 2 further including bracket means rigidly attached to said rotary for securing said lead means at right angles to said rotary, the

lower end portion of said lead means being pivoted to said bracket means in a manner to enable lateral movement of the upper end portion thereof while remaining square with said rotary.

4. The drilling attachment of claim 2 further including means for slidably guiding said drive kelly along said lead means to stabilize said drive kelly during rotation thereof.

5. The drilling attachment of claim 4 wherein said drive kelly includes an inner member telescopically disposed within an outer member, said rotary engaging said outer member, and roller means mounted at the lower end of said outer member and engaging said inner member to transmit torque to said inner member and enable said inner and outer members to telescope freely during a drilling operation.

6. A drilling attachment for use in conjunction with a crane having an upwardly extending boom, comprising, a horizontally disposed frame assembly including a main frame adapted for connection to the crane at the base of the boom and extending outwardly underneath the boom, and a slidable frame movable longitudinally along said main frame between various fixed positions in relation thereto; a drilling unit mounted on said slidable frame and including a rotary attached for pivotal rotation about a horizontal axis, and a drive kelly extending through said rotary and adapted to be rotated thereby; lead means secured at right angles to said rotary and extending upwardly for suspension from the boom, said lead means being tilted in response to changes in boom angle and in response to longitudinal movement of said slidable frame along said main frame, tilting of said lead means functioning to automatically pivot said drilling rotary about said horizontal axis to establish a desired drilling angle; and means for adjusting the distance between the upper end of said lead means and its point of suspension from the boom in order to maintain said main frame and said slidable frame in a substantially horizontal disposition for any desired drilling angle.

7. The drilling attachment of claim 6 wherein said lead means and said drive kelly extend in parallel alignment, and further including guide means for maintaining said parallel alignment and for stabilizing said kelly during rotation.

8. The drilling attachment of claim 7 wherein said guide means includes a bushing assembly rotatably receiving the upper end portion of said kelly, and slide means connected to said bushing assembly and slidably engaging said lead means.

9. A drilling apparatus for use in conjunction with a crane having an upwardly extending boom, comprising: a horizontally disposed frame assembly including a first frame attached to the crane at the base of the boom and extending outwardly underneath the boom, and a second frame; a slide assembly including longitudinally extending runners for mounting said second frame on said first frame, said second frame being movable longitudinally along said first frame between various positions relative thereto; means for fixing the position of said second frame along said first frame; a drilling unit mounted on said second frame for movement therewith and including a rotary carried by trunnions for pivotal rotation about a horizontal axis that is transverse to said frame assembly, and a kelly suspended from the boom and adapted to be driven by said rotary; a lead beam secured at right angles to said rotary and extending upwardly in parallel relation to said kelly, said lead beam being suspended from the boom so that changes in boom angle will cause tilting of said lead beam and reactive tilting of said rotary to extablish a desired drilling angle; means for adjusting the distance between the upper end of said lead beam and its point of suspen sion from the boom in order to maintain said first frame and said second frame in a substantially horizontal disposition for any desired drilling angle; and guide means secured to the upper end portion of said kelly and slidably engaging said lead beam to stabilize said kelly during rotation thereof.

10. The drilling apparatus on claim 9 further including a motor mounted on said second frame for driving said rotary, and a drive train from said motor to said rotary including an input shaft aligned with the pivot axis of said rotary.

11. The drilling apparatus of claim 9 wherein said guide means includes a bushing assembly rotable receiving the upper end portion of said kelly, said bushing assembly being attached to slide members movable longitudinally along said lead beam.

12. The drilling apparatus of claim 9 wherein said kelly includes an inner member telescopically disposed within an outer member, said rotary engaging and turning said outer member, and a roller guide assembly fixed to the lower end of said outer member and including roller means engaging said inner member to transmit torque thereto and enable free telescoping action during a drilling operation. 

1. A drilling apparatus adapted for attachment to a crane having an upwardly extending boom, comprising: a generally horizontally disposed frame assembly having coupling means at one end for pivotally attaching said frame assembly to the crane at the base of the boom; a drilling unit mounted for movement relatively along at least a portion of said frame assembly between various fixed positions with respect thereto, said drilling unit including a drilling rotary mounted for pivotal movement about a horizontal axis that is transverse with respect to said frame assembly; and rigid lead means extending upwardly from said rotary for suspending said drilling unit and said frame assembly from the boom, said lead means being attached at right angles to said rotary and functioning to tilt said rotary in response to changes in boom angle to establish a desired drilling angle.
 2. A drilling attachment for use in conjunction with a crane having an upwardly extending boom, comprising: a generally horizontally disposed frame assembly adapted to be pivotally connected to the crane at the base of the boom; a drilling unit mounted for movement relatively along at least a portion of said frame assembly between various fixed positions with respect thereto, said drilling unit including a drilling rotary attached for pivotal rotation about a horizontal axis that is transverse with respect to said frame assembly, and a drive kelly extending through said rotary; and lead means secured at right angles to said rotary and extending upwardly in parallel alignment with said drive kelly, said lead means being suspended from the boom in a manner to be tilted in response to changes in boom angle to automatically pivot said drilling unit and thereby establish a desired drilling angle.
 3. The drilling attachment of claim 2 further including bracket means rigidly attached to said rotary for securing said lead means at right angles to said rotary, the lower end portion of said lead means being pivoted to said bracket means in a manner to enable lateral movement of the upper end portion thereof while remaining square with said rotary.
 4. The drilling attachment of claim 2 further including means for slidably guiding said drive kelly along said lead means to stabilize said drive kelly during rotation thereof.
 5. The drilling attachment of claim 4 wherein said drive kelly includes an inner member telescopically disposed within an outer member, said rotary engaging said outer member, and roller means mounted at the lower end of said outer member and engaging said inner member to transmit torque to said inner member and enable said inner and outer members to telescope freely during a drilling operation.
 6. A drilling attachment for use in conjunction with a crane having an upwardly extending boom, comprising, a horizontally disposed frame assembly including a main frame adapted for connection to the crane at the base of the boom and extending outwardly underneath the boom, and a slidable frame movable longitudinally along said main frame between various fixed positions in relation thereto; a drilling unit mounted on said slidable frame and including a rotary attached for pivotal rotation about a horizontal axis, and a drive kelly extending through said rotary and adapted to be rotated thereby; lead means secured at right angles to said rotary and extending upwardly for suspension from the boom, said lead means being tilted in response to changes in boom angle and in response to Longitudinal movement of said slidable frame along said main frame, tilting of said lead means functioning to automatically pivot said drilling rotary about said horizontal axis to establish a desired drilling angle; and means for adjusting the distance between the upper end of said lead means and its point of suspension from the boom in order to maintain said main frame and said slidable frame in a substantially horizontal disposition for any desired drilling angle.
 7. The drilling attachment of claim 6 wherein said lead means and said drive kelly extend in parallel alignment, and further including guide means for maintaining said parallel alignment and for stabilizing said kelly during rotation.
 8. The drilling attachment of claim 7 wherein said guide means includes a bushing assembly rotatably receiving the upper end portion of said kelly, and slide means connected to said bushing assembly and slidably engaging said lead means.
 9. A drilling apparatus for use in conjunction with a crane having an upwardly extending boom, comprising: a horizontally disposed frame assembly including a first frame attached to the crane at the base of the boom and extending outwardly underneath the boom, and a second frame; a slide assembly including longitudinally extending runners for mounting said second frame on said first frame, said second frame being movable longitudinally along said first frame between various positions relative thereto; means for fixing the position of said second frame along said first frame; a drilling unit mounted on said second frame for movement therewith and including a rotary carried by trunnions for pivotal rotation about a horizontal axis that is transverse to said frame assembly, and a kelly suspended from the boom and adapted to be driven by said rotary; a lead beam secured at right angles to said rotary and extending upwardly in parallel relation to said kelly, said lead beam being suspended from the boom so that changes in boom angle will cause tilting of said lead beam and reactive tilting of said rotary to extablish a desired drilling angle; means for adjusting the distance between the upper end of said lead beam and its point of suspension from the boom in order to maintain said first frame and said second frame in a substantially horizontal disposition for any desired drilling angle; and guide means secured to the upper end portion of said kelly and slidably engaging said lead beam to stabilize said kelly during rotation thereof.
 10. The drilling apparatus on claim 9 further including a motor mounted on said second frame for driving said rotary, and a drive train from said motor to said rotary including an input shaft aligned with the pivot axis of said rotary.
 11. The drilling apparatus of claim 9 wherein said guide means includes a bushing assembly rotable receiving the upper end portion of said kelly, said bushing assembly being attached to slide members movable longitudinally along said lead beam.
 12. The drilling apparatus of claim 9 wherein said kelly includes an inner member telescopically disposed within an outer member, said rotary engaging and turning said outer member, and a roller guide assembly fixed to the lower end of said outer member and including roller means engaging said inner member to transmit torque thereto and enable free telescoping action during a drilling operation. 